Next Step: The Gulf War : U.S. Technology Has Worked in Air, Will It Work on Ground? : Some military analysts are concerned that the U.S. arsenal has not been sufficiently proven.

As U.S. and allied military forces in the Persian Gulf contemplate shifting from an air campaign to a massive ground engagement, some independent military analysts caution that the amazing technical efficiency those forces have demonstrated in the skies may not continue closer to earth.

Although many proponents of air power argue that the massive bombing will cause Iraq to withdraw from Kuwait, and thereby eliminate the need for an invasion, many analysts predict that a bloody ground assault is inevitable.

Some critics contend that much of the U.S. military arsenal has not been sufficiently proven, and that many highly criticized weapons systems, such as the M-1A1 tank, the Apache attack helicopter and the Bradley fighting vehicle, could present unforeseen difficulties.

"The battlefield is no place to find out how good these systems are," said James Burton, a retired colonel who did armored vehicle testing for the Army.

No matter how many tests a new system has gone through, it is going to perform differently in a combat situation, when its operators are stressed and conditions are less than optimum, added Piers Wood, a former Army artillery officer who is chief of staff for the Center for Defense Information, a Washington think tank that has opposed U.S. involvement in the conflict between Iraq and Kuwait.

"When bullets start snapping around you, you're in a different element," Wood said.

Still, Burton said, "If our guys are good enough and quick enough to adjust to the problems, they will be all right."

The manufacturers and the Pentagon contend that the critics exaggerate the potential problems. And to the extent the equipment does work, all agree it is likely to have profound effects.

"It is going to be the type of warfare people never realized, or could have expected," Brig. Patrick Cordingly, the head of Britain's armored brigade in Saudi Arabia, told a press conference recently. "Modern equipment and the effect it has are more powerful than in any previous war. The results are going to be fairly terrific when they are used."

"I believe that with all things working and going well, we could conduct something as brilliant as the Six-Day War," Wood said, referring to the conflict between Israeli and Arab forces in 1967. "But let's not kid ourselves. It's probably more likely to turn out like the Falklands War."

Wood said the British competently executed the 1982 Falklands War against Argentina, but they still suffered significant casualties and lost a destroyer.

For U.S. forces in the Persian Gulf, one of the biggest potential problems is the 63-ton M-1A1 tank, the mainstay of the U.S. ground forces. The 120-millimeter cannon on the $3-million tank fires long metal rods of tungsten or uranium designed to melt or vaporize tank armor that they hit, sending a lethal shower of molten metal into the interior. Unlike older tanks, the M-1A1 can fire its guns even when it is on the move.

But "according to the Army's own documentation, it just doesn't do what it is supposed to do," said Kevin Page, a research associate at the Project on Government Procurement, a self-styled military reform group that has prepared a report cataloguing the tank's perceived shortcomings.

The weak link of the tank is its powerful turbine engine, which proponents say gives it unprecedented speed and agility on the battlefield. "But it's more complicated than a conventional diesel engine, uses much more filtered air and uses more fuel," said the project's Greg Williams, who wrote the M-1A1 report. Congressional critics have made similar charges.

In fact, the M-1A1 requires about nine gallons of fuel for every mile traveled over the desert, more than twice as much as comparable German tanks need, Williams said. "You're going to have bunches of unarmored fuel trucks running around in rear areas to keep it supplied," he said.

The massive amount of air required for the turbine must be heavily filtered to protect the motor, and those filters clog up even in normal operating conditions. In the desert, Williams said, it is likely that tank crews will have to shut down their engines frequently and get out to clean the air filters.

All that air is also exhausted at temperatures so high that crew members are warned not to get near the exhaust without protective clothing. The exhaust gives the tank a "heat signature" that could render it unusually vulnerable to heat-seeking missiles.

The tank has also exhibited severe maintenance and reliability problems. During training exercises, according to Army reports, it suffered a failure of some sort--either mechanical or electrical--every 21 minutes and a disabling breakdown every 151 miles, about twice as often as older tanks.